Due to more than average global warming in Greenland the melting of smaller so-called peripheral are increasing. (Photo: W. Colgan/GEUS)

Earth's northernmost glaciers are melting at record speed

Friday 17 Jun 22

Contact

Shfaqat Abbas Khan
Professor
DTU Space
+45 45 25 97 75

Greenland's Peripheral glaciers

In Greenland, there are many smaller glaciers that are not connected directly to the Greenland Ice Sheet itself. They are called peripheral glaciers and there are an estimated 20,300 of them.


All these glaciers have their own mass balance, as is the case with the Greenland Ice Sheet. The mass balance is the ratio between melting in summer and snowfall in winter. If the mass loss (melting) is greater than the mass supply (snowfall), the glacier becomes smaller, and vice versa.


Read the scientific article in Geophysical Research Letters

The melting of Greenland's many smaller glaciers is increasing, and it now sends 15 billion tons extra of water into the sea annually, according to new research led by DTU.

A new study focuses on the melting of smaller glaciers that are not connected to the main Greenland Ice Sheet. These so-called peripheral glaciers make up only about four percent of Greenland's ice-covered areas, but they contribute as much as 11 percent of the total loss of ice from Greenland's ice-covered areas. Thus, they are a major contributor to global sea level rise.

The new research cover parts of the past two decades. It shows that on average, 42.3 gigatons (billion tons) of ice melted annually from October 2018 to December 2021. In comparison, 27.2 gigatons melted annually in the period February 2003 to October 2009. This is an annual increase of 15 billion tons or 55 per cent on average.

"The loss of ice from these small glaciers occurs because they are more sensitive to ongoing temperature changes and therefore melt faster than we see in many other places in the Arctic," says Professor Shfaqat Abbas Khan from the Geodesy and Earth Obervation division at DTU Space, Denmark. He is the lead author of a paper on the new research that has just been published in Geophysical Research Letters.

“We can see that there is a marked increase in the melting of these glaciers in northern Greenland. This shows that the ice masses in Greenland are very unstable and that they contribute considerable to the global sea level rise.”

The research has been conducted in international collaboration between DTU Space, the Geological Survey of Denmark and Greenland (GEUS), NASA Goddard Space Flight Center, Utrecht University, University of Bristol and the University of Copenhagen.

The changes have been recorded using altimetry (altitude measurements) with the American climate satellites ICESat and ICESat-2.

In the Arctic, temperatures are rising more than in the rest of the world, and this is causing these northernmost glaciers in Greenland to melt at record speed.

”It is disturbing, but to be expected, that the northernmost ice sheet on the planet is hit hard by the ongoing temperature rises, because it is evident that the temperature here has also risen the most in the last 20 years,” says Shfaqat Abbas Khan.

Focus on melting from the peripheral glaciers

Although the isolated peripheral glaciers are not part of the Greenland Ice Sheet, it is important to include them in the total melt budget from the Arctic in order to calculate exactly how much the region contributes to sea level rise. 

Compared to the Greenland Ice Sheet, there is relatively little research on the peripheral glaciers. The researchers new study will help change that.

“It is important to keep track of all sources, especially because there are large variations in the melting patterns in different parts of Greenland,” says Senior Researcher and co-author of the new study, William Colgan from the National Geological Survey of Denmark and Greenland (GEUS).

“Many studies have documented the state of the Greenland Ice Sheet over the past decade. But even though the loss of ice from peripheral glaciers is such a large part of Greenland's total ice loss, there are very few studies documenting the 'health' of these peripheral glaciers. In fact, ours is the first altitude measurement of Greenland's peripheral glaciers with laser satellites since 2013”.

A complex and varied picture

Overall, there is a large net melting of the ice in Greenland because of global warming, which hits Greenland and the Arctic harder than other regions of the world. But the picture is very complex and varied.

“There are areas in East Greenland where more precipitation in the form of snow has balanced the ice mass loss, so that it is not nearly as large as in northern Greenland. Areas in East Greenland with mountains of over 2,000 metres in height have for example had increased precipitation in high-altitude areas,” says William Colgan.

“However, this is more than offset by the proportionally very heavy melting from the peripheral glaciers in North Greenland in particular”.

https://www.oceandecade.dk/news/nyhed?id=a48d3acd-fd7a-481b-9c30-15ec642dd1cb
27 SEPTEMBER 2022